


Stuck On You

by SleepyHailey



Category: Undertale (Video Game)
Genre: Biology, F/F, Post-Undertale Pacifist Route, smells like Undyne, smells like nerd, smooches
Language: English
Status: Completed
Published: 2020-04-15
Updated: 2020-04-15
Packaged: 2021-03-01 20:53:37
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,327
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23673394
Author URL: https://archiveofourown.org/users/SleepyHailey/pseuds/SleepyHailey
Summary: Alphys and Undyne have a romantic night in and decide to take it to the next level. But nothing is ever easy.
Relationships: Alphys/Undyne (Undertale)
Comments: 4
Kudos: 21





	Stuck On You

“Senpai,” she whispered breathlessly, the rain soaking into her white coat. “I want you to _touch_ me.”

“So bold,” the taller girl replied coolly. “What brought this on?”

The short girl’s glasses fogged up, hiding her eyes. “My feelings for you are too much for words. That’s why I couldn’t tell you. I understand if you can’t forgive me.”

The tall girl’s umbrella fell to the rain slicked street. In an instant, she had the short, stout girl in her arms. “Baka,” she said before her lips were planted, hungrily, on the lips of her love.

“This is so friggin’ hot,” shouted a shrill, piercing voice.

From across the anime stricken tv screen sat Undyne, a tall, one-eyed fish monster. Next to her sat Alpyhs, her chubby, saurian girlfriend. Clad in their pajamas, the sapphic monsters sat on their ratty couch in their sparsely, yet tastefully, decorated apartment. Alphys, wearing an oversized t-shirt bearing a smiling cat girl on the front, lay halfway across Undyne’s white boxer short covered lap. Alphys’ head frills pressed into the black tank top that covered Undyne’s taut tummy. Undyne absently stroked the tips of Alphys’ frill as she shouted excitedly at the anime girls on the TV.

On the screen, the tall japanese school girl’s hands were climbing under the other girl’s shirt. Undyne leaned forward suddenly, nearly throwing Alphys to the floor. She looked up to see Undyne’s wide toothy grin.

“Oh man, you think they’re gonna do it right there in the street,” Undyne asked, wringing her webbed hands.

Alphys blushed and mumbled a reply that sounded something like, “gfdhgjfd.” She painstakingly pulled her bespectacled eyes from her shining scaled goddess and back to the screen. The scene had transitioned from the streets back to the nearby apartment of the tall girl. The two were lying in bed, embracing one another, the blanket strategically covering their nude forms.

“Weak,” Undyne huffed, slamming her ankles down on the low coffee table with a crack. She let her hands flop down onto Alphy’s side. “If you’re trying to show passion, you can’t hold anything back! You can’t just cut away as soon as it gets to the good part!”

The furious Undyne balled her hands into fists and started punching the air. “That’d be like if they skipped all the fighting robot parts and just showed the whiny kid jerking off in the hospital! Don’t they understand what their audience wants? I can accept anime not being real, but I refuse to accept it being crap!”

“I think it’s cute,” Alphys haltingly said into Undyne’s exposed thigh. She immediately clamped her beaked mouth shut, regretting the dissent.

Undyne looked down, an impassioned retort at the edge of her tongue, ready to cut through the injustice of incorrect opinions. The sight of the blushing, nerd-lizard, biting her lower lip sheathed Undyne’s outrage. She wrung her hands as her eye darted back to the tv.

“It’s just that they’re just _talking_ again,” Undyne said, forcibly cooling the anime-born fury deep inside. “We’ve seen them _talk_. I wanna see the other stuff.”

From her lap, Alphys muttered something inaudible and let out a gasp. Undyne looked down to see that her girlfriend had pulled the collar of her shirt halfway over her face. With a teasing, jagged tooth sneer, Undyne cupped a hand to her finned ear.

Slowly, agonizingly, Alphys pulled her collar down so that it was only covering the tip of her beak. Stuttering and red faced, Alphys said “We could fill in the gaps, if you want.”

The remote crunched in Undyne’s hand as she jammed the pause button through its surface. Alphys watched the debris of the remote crumble through Undyne's fingers and fall like snow onto the carpet.

“Is that a no?” Alphys asked, her voice rapid and anxious. “Because it's really okay if you don't want to or if this is too sudden or if you want to dump me or-”

“Freaking hell, shut up,” Undyne roared and hoisted the Alphys into the air by her shoulders. Bringing Alphys' face microns away from Undyne’s, her breath fogging Alphys’ glasses. With madness gleaming in Undyne's eye, she hissed, “I have been buying a box of condoms every freaking night for the last two months.”

Avoiding eye contact and sweating heavily, Alphys asked, “Do you know what condoms are for?”

Undyne threw her head back and cackled, “Of course.”

Holding Alphys up with one hand, Undyne jammed a clenched fist through the back of the couch, through the wall, and into the back of the dresser located in the adjacent room. She retracted her arm, flecked with stuffing, plaster, and wood splinters, to reveal a large box of condoms clenched in her fist. Undyne shoved the box in Alphys’ face so that it mashed against her beak.

“It says right on the box,” Undyne said proudly tapping a finger on the wording. “They're for 'her pleasure'!”

With considerable effort, Alphys managed to drag the box away from her face. “I'm sure we'll, uh,” she mumbled, looking down at her stubby claws, “Find something to do with those. Later.”

“More for me,” Undyne shouted before jamming the box into her mouth. She dropped Alphys on the couch next to her. “So, what did you, you know, want to do?” Undyne asked with a mouthful of latex and cardboard.

What she wanted to do was a question that Alphys had spent a long time contemplating. She'd fantasized, strategized, and memorized dozens of different approaches to this very moment. Back in the Hotland lab there was a red wig that her friend, Mettaton, refused to ever wear again locked up alongside a very graphically designed pillow.

“I guess we can start with kissing,” Alphys blurted and then covered her face with her hands.

“Aw yeah!” Undyne bellowed.

Undyne grabbed up Alphys once and dipped her so that Alphys’ frills were scraping against the carpet. Undyne puckered her lips and closed her eye as she leaned in. The smooches were unleashed.

For several ecstasy filled minutes, Alphys was a quivering ball of putty in Undyne's webbed hands. Alphys forced herself back to her senses. She had decided this was to be the moment. Smooches were great and always a fun way to spend the evening, but it was time for the big leagues. It was lizard-monster-on-fish-monster-lesbian-sex time and it was up to her to make it happen.

“Wait,” Alphys reluctantly whispered and pushed back against Undyne's chest. She opened her eye with a puzzled expression and righted Alphys before setting her on her feet.

“I'm getting some mixed signals here,” Undyne said quizzically. “Help me find the channel, do you want to do a little something-something or am I eating all these condoms for nothing?”

Looking down and clicking her index claws together, Alphys mumbled and circled her foot on the carpet, kicking up remote control debris.

Putting on a big grin, Undyne stood up and put a hand on top of Alpyh's crown. “It's okay if this is like, too fast or whatever,” Undyne said in a reassuring tone. “I'll just grab a spare remote and-”

With a strength fueled by all the gods of primal passion, Alpyhs shoved against Undyne with all her might. Undyne stood stationary, blinking, for several seconds before letting her grunting and panting lady love push her back to being seated on the couch. Alphys hoisted herself up and straddled Undyne’s leg. Alphys reached her hand up to Undyne’s face and she nuzzled against Alphys’ palm.

“I want to do this with you,” Alphys said after she finished wheezing, her face was flush from more than the physical effort.

Words gave way to action as Alphys began kissing Undyne, clumsy at first, but gaining confidence with each successive smooch. Starting at her lips, she moved from the corner of Undyne's mouth down her jaw. Undyne cooed and bit into her own hand as Alphys let her lips flutter down her gills and across her collarbone.

Alphys gripped the hem of Undyne's tank top and slid it upwards as her face dropped and buried into Undyne's tight stomach. She moved up, sliding the shirt with her as she went. Eyes shut, lost in ecstasy, Alyphs crossed the threshold that was the bottom of Unyne's ribs. She couldn't help herself as her hands shot upwards and grasped firmly onto Undyne's chest.

Undyne's entirely flat and nipple-less chest. Alphys opened her eyes to the blank canvas of fish scales before her.

Drawn out by the lapse in kisses, Undyne looked down to see Alphys curiously poking her pectoral muscles. “Yeah, I'm pretty cut,” Undyne said awkwardly. “But, if you could pick up where you left off...”

Shocked out of her stupor, Alphys resumed her affectionate attention in a downward direction. ' _I guess I should have seen that coming_ ,' she thought. ' _No mammaries on the fish waifu. Really shoulda realized that._ '

Back down at the gloriously toned fish belly, Alphys slid herself down Unyne's leg and onto the floor. Still kissing and nibbling her belly, she hooked her claws into the waist of Undyne's boxers. With a giddy tug, the undies went flying across the room, landing perfectly on top of the TV screen.

Alphys gazed lustfully down into Undyne's lap and went entirely still.

“Oh. My. God,” she mumbled, eye twitching.

Where Undyne's legs met her torso was nothing but shimmering scales. Alphys traced her claws over the crotch that was as featureless as the human dolls that tended to turn up in the dump back in the Underground. Closer examination revealed not but a small divot towards the bottom.

“Why are you staring at my pee hole,” Undyne asked, looking down with a confusion that bordered on horror. “If you're into that kinda stuff, we're gonna really have to talk first.”

Yelping and stumbling backwards, Alphys tumbled to the floor and bonked her head against the coffee table. Undyne shot to her feet and scrambled to check on the groaning Alphys.

“I'm sorry, I'm sorry.” Undyne cried. She knelt down and felt the back of Alphys' head for injury. “Please don't die, I didn't mean to kink shame you!”

“'m not dying,” Alphys mumbled and grabbed out to right herself. She grabbed something that was both firm and soft at the same time. A dopey smile crawled across her face as she realized she had a very firm grasp on Undyne's butt.

' _At least that's how it's supposed to be,_ ' she thought wistfully as she squeezed.

Towering above, Undyne wore an equally goofy expression before she shook her head while growling.

“Time out,” she called and yanked Alpyhs onto her feet by her frill. “I'm getting seriously confused here. I thought you wanted to frick frack, but you keep zoning and freaking out.”

Alpyhs was still absently groping Undyne's bottom. Under the glare of her girlfriend, she slowly removed her hand and looked down and away.

“I do want to, uh, get to the next level with you,” Alphys grumbled like a scolded child while shuffling her feet and clicking her claws together. “It's just...”

' _Don't say “It's not like in my anime”_ ' Alpyhs's mind hissed.

“It's,” Alphys began haltingly.

_'DON'T_ ,' her mind pleaded

“Not,” her words continued in spite of all reason.

' _WHY?!_ ' her mind let off one last cry of despair.

“Like. In. My. Anime,” she finished with an awkward smile. In the deepest recesses of her brain was endless screaming.

Undyne scratched her chin in contemplation. “Yeah, I get you.”

“Really?” Alphys asked in stunned disbelief.

“I mean, yeah,” Undyne said as she gestured at the TV that held the image of the Japanese school girls embracing in bed. “Those are all humans doing boring, lame, stupid, sexy things. We're monsters, we do exciting, cool, well educated, sexy things.”

“ _We're_ also pretty different,” Alphys added, rubbing a knuckle against Undyne's bare crotch. “I mean, does this even feel good?”

“You're touching me,” Undyne looked away with an embarrassed smile. “Of course it feels good!”

Alphys blushed and shyly rubbed the bridge of her nose. “Okay,” she said. “How's about this, you tell me what the most erotic and sensual thing I can possibly do for you is and I'll do it.”

After a drawn out pause, a blush crept onto Undyne's cheeks. “Really?” she asked with a crooked smile. “Anything?”

“Your wish is my command,” Alphys said, waggling her brows. “I am your erotic slave.”

“Okay,” Undyne was chewing her lip. “Go back to my belly.”

Fortunately, her belly was at roughly eye level for Alphys, so she did as she was told.

“Now go to my side,” Undyne commanded, as she bounced on her heels. “Right side, I wanna be able to see you,” she added quickly. “Now open your mouth. Wider. Wiiiiider. There you go.”

Alphys stood, facing Undyne's side, her mouth opened painfully wide. “Ow whagdt?”

Gently, Undyne placed her hand on Alphy's crown. She guided her to tilt her head sideways. With a tug, Alphys’ teeth were pressed firmly onto Unyne's side.

“Now bite down,” Undyne cackled. “Harder!”

Alphys clamped firmly onto Undyne’s side. After a minute, Alphys started to pull her mouth away to ask the next step. Undyne squeezed Alphys’ mouth shut even tighter on Undyne's side.

“Hey, don't let go!” Undyne chided.

Alphys pointed over at the arm of the couch and Undyne hoisted her up by the back of her shirt. The conjoined pair hopped over and Aphys grabbed her phone off the arm rest. She quickly tapped her claws against the screen.

“So what now?” Alphys asked using the cute voice option from the text-to-speech app on her phone.

“That's it,” Undyne bellowed with a smile. “You just stay latched on there. Forever!”

“Oh,” Alphys texted. “My god.”

“I know right,” Undyne laughed, jostling Alphys like an underarm barrel of weeaboo, “This is so friggin' hot!”

'This _really_ isn't like my anime.' Alphys did not text that.

<3

**Author's Note:**

> The joke is fish biology.  
> https://www.youtube.com/watch?v=Z-BbpaNXbxg  
> Pic done for the fic by my dear friend:  
> https://twitter.com/BangDacy/status/1250571431479398400?s=20


End file.
